   (#{DayOfWeek/SATURDAY DayOfWeek/SUNDAY} (day-of-week zdt)))
 
 (defn- easter-sunday-by-year
-  "Return a pair containing [month day] of Easter Sunday given the year."
+  "Return a pair containing [month day] of Easter Sunday given the
+  year. Copyright © 2016 Eivind Waaler. EPL v1.0. From
+  https://github.com/eivindw/clj-easter-day, using Spencer Jones
+  formula."
   ;; TODO: From what year does this algorithm makes sense from, need
   ;; to throw an exception outside this range.
   [year]

                           :state (atom {})
                           :executor (or executor (new ScheduledThreadPoolExecutor 16))})))

(defrecord FixedClockAdvancingTicker []
  ITicker
  (start [this clock] nil)
  (pause [this] nil)


;; ???
(defn simulate []
  ;; Create a map->ImpatientTicker
  )


